Source Naturals Mushroom Immune Defense is a blend of mushroom mycelia and extracts from 16 of the most well-studied species of health-supportive mushrooms. Although the exact mechanisms of action in the body are not yet fully understood, researchers propose that constituents of these mushrooms support immune health. By carefully combining these mushrooms and fortifying them with extracts, Source Naturals Mushroom Immune Defense offers a broad-spectrum, high potency, complete mushroom product.